1. Field of the Invention
The present invention relates to an apparatus and method for displaying three-dimensional (3D) image and, more particularly, to an apparatus and method for displaying a 3D image capable of constantly displaying a 3D image by synchronizing a left-eye image and right-eye image and a display device.
2. Description of the Related Art
Services to be realized for a high speed transmission of information formed based on a high speed information communication network are advancing from a simple ‘listening and speaking service’ such as that of the current communication device to a multimedia service based on a digital terminals that processes text, voice, images at a high speed. Eventually, services are expected to be advanced to a superspace realistic 3D stereoscopic information communication service allowing users to feel and enjoy realistically and three dimensionally beyond time and space.
In general, a stereoscopic image representing three dimensions is displayed based on a stereoscopic visual principle through the user's two eyes. Because the parallax between the two eyes, namely, a binocular parallax, generated because the user's two eyes are away by about 65 mm, is a key factor of a stereoscopic sense. Namely, the left and right eyes see mutually different 2D images, and when the two images are transferred to the user's brain through the retina, the user's brain precisely unites the two images to reproduce a depth sense and a realistic sense of the original 3D image.
Such capability is generally called stereography. Currently, a technique proposed to display a 3D stereoscopic image on a 2D screen image includes a glassless stereoscopic (or autostereoscopic) image display scheme, a holographic display scheme, a glass type stereoscopic image display scheme based on time division, and the like.
The glassless stereoscopic image display scheme may be divided into a parallax barrier scheme in which images are separately observed through an aperture in a vertical lattice-like shape in front of the respective images corresponding to the left and right eyes, a lenticular scheme using a lenticular plate including semicircular lenses arranged, and an integral photography scheme using a lens plate having the shape of a fly's eye.
The holographic display scheme can obtain a 3D stereoscopic image having all the factors, such as focusing, auditory parallax, binocular parallax, motion parallax, and the like, which generates a stereoscopic sense, and it is classified into a laser reproduction hologram and a white light reproduction hologram.
The glassless stereoscopic image display scheme is advantageous in that the user does not need to put on glasses but has a problem in that an observation range is fixed to be limited to a small number of users and a stereoscopic image is not smoothly implemented according to positions of observers (or users).
The holographic display scheme is advantageous in that a 3D stereoscopic image can be displayed regardless of locations from which the image is viewed and a plurality of observers can use it simultaneously. However, because laser reference light must be additionally used to display a 3D image, it has a problem in that there is a difficulty in terms of technique and the space occupied by equipment is increased.
Meanwhile, the glass type stereoscopic image display scheme based on time division employs special glasses such as time division glasses, allowing a large number of users to enjoy stereoscopic images regardless of their locations.
The stereoscopic image display scheme based on special glasses includes a display scheme using shutter glasses and a display scheme using a phase retardation plate. In the display scheme using shutter glasses, while a left eye image is being displayed, a left eye part of the shutter glasses allows light to transmit therethrough and a right eye part blocks light. Also, while a right eye image is being displayed, the right eye part of the shutter glasses allows light to transmit therethrough and the left eye part blocks light.
In the display scheme using a phase retardation plate, a phase retardation plate is disposed on a front surface of a display panel, so while the right eye image is being displayed, the phase retardation plate is turned on (or off) to polarize light in one direction, and while the left eye image is being displayed, the phase retardation plate is turned off (or on) to polarize light in another direction, and in this case, the user wears polarization glasses, and a polarization plate having an optical axis parallel to a polarization direction of light when the phase retardation plate is turned on is provided at the right side and a polarization plate having an optical axis parallel to a polarization direction of light when the phase retardation plate is turned off is provided at the left side to alternately recognize images with his right and left eyes, thus implementing a stereoscopic image.
However, the time division stereoscopic image display scheme as described above has the following problem.
That is, in the time division stereoscopic image display scheme having the foregoing configuration, the left eye image is recognized with the left eye and the right eye image is recognized with the right eye, thus implementing a stereoscopic image. Thus, when the display device implementing an image, a system (an electronic device such as a television or the like) in which the display device is installed, and image data are not synchronized, the left eye image may be recognized by the right eye or the right eye image is recognized by the left eye, failing to implement a stereoscopic image.
Thus, in order to solve the problem, a reset button is provided. That is, when the synchronization is not made, a resetting operation is performed to return the display device to an initial synchronized state. In this case, however, as time goes by, the display device, the system, and the image data are not synchronized, so the resetting operation must be repeatedly executed, and because the resetting operation itself is performed by the user by directly manipulating the button, making the user feel inconvenient.